...got a bunch of people to come back in to test our forum ...
and many could not get the system to return their password to them.

The system gives them the following error (screen layout edited for readability here)
------------------start c-a-p ---------------------------------

A fatal error has occurred:

GT::Mail (32967): Wrong argument passed to this subroutine.
Usage: $obj->send (%opts); smtp or sendmail and a head part must exist at
this point. at /www/p/ptegler/cgi-bin/admin/GForum/User.pm line 489.

Please enable debugging in setup for more details.

------------------ end c-a-p ---------------------------------

I've gone in and turned on debugging and got a screen full, as well as having
added the < dump> box on the page to see all variables.

I don't see any variable not filled in proplery. What is/could not be being passed.

This is just the user clicking on the 'set temporary password' button on the
gforum.cgi?do=lost_password; screen.

ptegler